• 69……………. . A cloud-zappers B atoms C storm clouds D mirrors E
  • READING PASSAGE 13 Collecting Ant Specimens
  • Few words to say about this book




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    THE-BIBLE-OF-IELTS-READING-BOOK

     
    Questions 63-65 
    Complete the sentences below.
    Choose 
    NO MORE THAN TWO WORDS
     from the passage for each answer.
    63
    EPRI receives financial support from
    …………………. 
    64
    The advantage of the technique being developed by Diels is that it can be used
    ……………..
    65
    The main difficulty associated with using the laser equipment is related to its
    ………………..
     
     
    Questions 66-69 
    Complete the summary using the list of words,
     A-I
    , below.
    In this method, a laser is used to create a line of ionisation by removing 
    electrons from 
    66……………
    This laser is then directed at 
    67……………….
    in order to control 
    electrical charges, a method which is less dangerous than using 
    68…………….
    As a protection for 
    the lasers, the beams are aimed firstly at 
    69…………….

    A
    cloud-zappers
    B
    atoms 
    C
    storm clouds 
    D
    mirrors 
    E
    technique 
    F
    ions 
    G
    rockets 
    H
    conductors
    I
    thunder 


    110 
    READING PASSAGE 13 
    Collecting Ant Specimens 
    Collecting ants can be as simple as picking up stray ones and placing them in a glass jar, or as complicated as 
    completing an exhaustive survey of all species present in an area and estimating their relative abundances. The 
    exact method used will depend on the final purpose of the collections. For taxonomy, or classification, 
    long series, from a single nest, which contain all castes (workers, including majors and minors, and, if present, 
    queens and males) are desirable, to allow the determination of variation within species. For ecological studies, 
    the most important factor is collecting identifiable samples of as many of the different species present as 
    possible. Unfortunately, these methods are not always compatible. The taxonomist sometimes overlooks whole 
    species in favour of those groups currently under study, while the ecologist often collects only a limited 
    number of specimens of each species, thus reducing their value for taxonomic investigations.
    To collect as wide a range of species as possible, several methods must be used. These include hand collecting, 
    using baits to attract the ants, ground litter sampling, and the use of pitfall traps. Hand collecting consists of 
    searching for ants everywhere they are likely to occur. This includes on the ground, under rocks, logs or other 
    objects on the ground, in rotten wood on the ground or on trees, in vegetation, on tree trunks and under 
    bark. When possible, collections should be made from nests or foraging columns and at least 20 to 25 
    individuals collected. This will ensure that all individuals are of the same species, and so increase their value 
    for detailed studies. Since some species are largely nocturnal, collecting should not be confined to daytime. 
    Specimens are collected using an aspirator (often called a pooter), forceps, a fine, moistened paint brush, or 
    fingers, if the ants are known not to sting. Individual insects are placed in plastic or glass tubes (1.5-3-0 
    ml capacity for small ants, 5-8 ml for larger ants) containing 75% to 95% ethanol. Plastic 
    tubes with secure tops are better than glass because they are lighter, and do not break as easily if mishandled. 
    Baits can be used to attract and concentrate foragers. This often increases the number of individuals collected 
    and attracts species that are otherwise elusive. Sugars and meats or oils will attract different species and 
    a range should be utilised. These baits can be placed either on the ground or on the trunks of trees or large 
    shrubs. When placed on the ground, baits should be situated on small paper cards or other flat, light-coloured 
    surfaces, or in test-tubes or vials. This makes it easier to spot ants and to capture them before they can escape 
    into the surrounding leaf litter. 
    Many ants are small and forage primarily in the layer of leaves and other debris on the ground. Collecting 
    these species by hand can be difficult. One of the most successful ways to collect them is to gather the leaf 
    litter in which they are foraging and extract the ants from it. This is most commonly done by placing leaf litter 
    on a screen over a large funnel, often under some heat. As the leaf litter dries from above, ants (and other 
    animals) move downward and eventually fall out the bottom and are collected in alcohol placed below the 
    funnel. This method works especially well in rain forests and marshy areas. A method of improving the catch 
    when using a funnel is to sift the leaf litter through a coarse screen before placing it above the funnel. This 
    will concentrate the litter and remove larger leaves and twigs. It will also allow more litter to be sampled when 
    using a limited number of funnels. 
    The pitfall trap is another commonly used tool for collecting ants. A pitfall trap can be any small container 
    placed in the ground with the top level with the surrounding surface and filled with a preservative. Ants are 
    collected when they fall into the trap while foraging. 
    The diameter of the traps can vary from about 18 mm to 10 cm and the number used can vary from a few to 
    several hundred. The size of the traps used is influenced largely by personal preference (although larger sizes 
    are generally better), while the number will be determined by the study being undertaken. The preservative 
    used is usually ethylene glycol or propylene glycol, as alcohol will evaporate quickly and the traps will dry 
    out. 


    111 
    One advantage of pitfall traps is that they can be used to collect over a period of time 
    with minimal maintenance and intervention. One disadvantage is that some species are not collected as they 
    either avoid the traps or do not commonly encounter them while foraging.

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